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    <title>Document</title>
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<body>
    <script>
        var a = 1; // a = 3
        // 2 + 3 + 1  //6
        var sum1 = ++a + ++a + 1;
        console.log('sum1: ', sum1);


        var b = 1;//b = 3
                    1  +  2 +1
        var sum2 = b++ + b++ + 1;
        console.log('sum2: ', sum2);//4/3
    </script>
</body>

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